I was knocked out once play wrestling with my friend in the school yard. I hit my head on the ground and blacked out. The next thing I remember is coming to my senses outside the school, leaning over my friends shoulder. I concluded I must have passed out from the trauma, but here's the interesting detail.

I hadn't passed out. My friend told me I was awake the entire time, and even talking to him. Some people who witnessed the event corroborated the story. I never lost consciousness!

So it appears head trauma "switches off" your long term recording mechanisms, so even though you are awake, you will not "record" anything in your memory and that part of your life will just be a blank space that your brain will skip to the next recorded event.

This leads me to believe that all our theories about brain trauma leading to loss of consciousness are not completely grounded in fact. The real test would be to measure brain activity through some sort of scanning device during head trauma. If we are going just on the fact that people blank out after head trauma, that's not good enough. People may well be conscious through out the entire event but only fail to remember it later.